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Expert Q&A

Why do I need bifocals? Can I avoid them?

Asked by Claire, Decatur, Georgia

I have worn glasses for nearsightedness since I was 15. I recently turned 40 and sometimes have trouble focusing on small things close up (such as text messages on my cell phone or restaurant menus). My eye doctor says I may need bifocals. Why did this happen and what can I do to avoid wearing bifocals?

Expert answer

Thanks for your question. As we age, many of us notice difficulty reading small items within a meter (or few feet) of our eyes. This issue can become more pronounced after the age of 40, when the lenses of the eyes become progressively less flexible and have trouble accommodating to focus on objects at different distances.

I consulted with Dr. Ravi D. Goel, a comprehensive ophthalmologist in Cherry Hill, N.J., and an instructor on the cataract and primary eye care service at the Wills Eye Institute. He shared the following analogy:

"Think of the lens system of the eyes as you would a trampoline. When you're young, the lens (the center of the trampoline) is held in place by lens zonules (the strings of the trampoline). The lens zonules are strong and they are able to move back and forth to bring images into focus. As you grow older, these "strings" start to relax, which makes it more difficult for you to control the movement of the lens to bring an image into focus. As these lens zonules relax, you can either hold an object farther away or use bifocals to bring an image to a more comfortable position. Bifocals are the cure for arms that are not long enough."

Some people who are just noticing difficulty viewing near objects can continue without bifocal glasses for several years. It may, however, take a few seconds to adjust one's focus when looking at a faraway object and then at something close. For people with just occasional difficulty seeing close up, some of my colleagues suggest using a pocket-size magnifying glass for reading small text and then your usual single-vision glasses/contacts for everything else, such as driving or watching television. Still others use two pairs of glasses (one for far distance and one for near) and switch back and forth as needed.

When quick fixes such as these become inconvenient or inadequate, Goel notes, there many other refractive options to consider. Progressive lenses make a smoother transition between as many as 20 different focal points in the glasses (for clearly viewing varying distances) compared with conventional bifocal lenses, which typically have a line dividing two parts (or trifocals, which have three parts) within the glasses. While wearing bifocal contact lenses in both eyes is a common choice, some people may prefer to wear a distance vision contact lens in one eye and a bifocal contact lens in the other to suit their individual needs. You may also wish to consult your ophthalmologist to see whether refractive surgery (such as LASIK) might be an option to treat your nearsightedness, allowing you to use reading glasses only when needed.

Good luck!

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